I use Ninject for my personal projects and I find it to be good, as it has a lot of documentation. Lot of people are using it and so it's easier to find information and also best practices with respect to the usage of ninject. For instance, my website uses ninject for dependency injection and few of my future personal projects use ninject extensively. I am also planning on improvising my site as I have learned much more about ninject as at that time I was just getting started with it. I am still learning a lot with respect to ninject. I do not use any other DI frameworks and so can't really compare them, but, so far I am convinced and happy with ninject. Just my 2 cents regarding ninject. Sorry if it was not helpful.
As a side-note refer to this SO post - http://stackoverflow.com/questions/4538625/dependency-injection-frameworks-for-net